Whisk eggs, pepper, and garlic powder in a medium bowl until well combined.
Heat oil in a large skillet over medium heat. Add spinach; cook until wilted, 1 to 2 minutes. Add the egg mixture and scallions; cook, stirring occasionally, until the eggs are just set, about 3 minutes.
Divide the egg mixture, feta, beans, and tomato among the tortillas. Roll each tortilla snugly, tucking in the ends as you go. Wrap each in heavy-duty foil, label, and freeze.
To serve, unwrap one burrito, discard foil, and place on a microwave-safe plate. Cover with a paper towel and microwave on High until steaming hot throughout, 1 to 2 minutes. Repeat for additional burritos, as needed.